In co-pending U.S. patent application Ser. No. 919,943, an assisted braking device is described which comprises a master piston mounted for sliding in a master cylinder, a jack having a piston connected to the master piston by interconnecting means, a source of assisting hydraulic pressure, and a distributor adapted to supply the jack with assisting hydraulic pressure from the said source and operated in response to the actuation of pilot means comprising a pedal, wherein the pedal is located at one end of a lever which is directly mounted by an articulation on the interconnecting means, the other end of the lever acting on the distributor.
If the assistance should fail, manual intervention can be provided by means of the pedal.
In the aforesaid patent application, this manual intervention is made possible by the abutting of a flange of the slide-valve of the distributor against a bearing surface of the body of the distributor. Consequently, the pedal action occurs with the same reduction ratio whether or not the assistance is defective.
This invention relates to an assisted braking system in which, in the case of the failure of the assistance, manual operation by means of the pedal is effected with a greater reduction ratio, which reduces the pedal load and makes it easier for the user to intervene manually.